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Study on D0 cross-feed using power law PT with open cuts to avoid bias. Analysis based on nsigma of daughters and PT of D0, with improvements seen using tighter nsigma cuts. Details on PT dependence of cross-feed in different cosine theta ranges.
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Quantification of D0 cross-feed J. Bouchet
outline • Use single D0 with power law pT • MuKpi used with “ open cuts”, to not bias the results • The misidentified D0 are reconstructed with (K+,π-) (due to PID) then the xfeed is estimated as : # (K+,π-) / #(K-,π+)+#(K+,π-) • Study as a function of nsigma(dEdX) of daughters and pT of D0 (at nsigma fixed) • Second part of study is done as a function of cosine(theta*)
Inv. Mass VS ndEdx cut * Green line is a fit using double gaus
summary *we see from the inv. Mass plots some entries far from the expected D0 mass ; counting in a restricted range to avoid fakes. *Nsigma cut used in 3th production
(dEdx vs P) VS pTD0 cut In this part ,ndEdx is fixed at |ndEdx|<3 for both daughters
comments • The xfeed is improved when the cut on the nsigma is tigher : • Obvious since with this cut the PID of daughters is better • It also decreases VS pT of D0 : from slide 6 we see that selecting D0 with pT>2 gives a better PID selection (dEdx band are not overlapping as for pT D0 <0.5) • Next slide : study as a function of cosine(theta*) • Plots of the cosine(theta*) for all entries and fake D0, as a function of reconstructed pT D0
comments • Slide 10 : we see that the misidentified D0 have a cosine(theta*) distribution reduced [-0.8,0.8] when pT of D0 increases, • whereas the distribution for true D0 remains (in the statistic here) flat over [-1,1] for the pT bins studied here (statistic became low for pT D0>2) • Next slide is just the 2d plots for cosine(theta*) vs inv. Mass for these pT bins
Cosine(theta*) vs inv mass VS pTD0 cut 0<pT<0.5 0.5<pT<0.1 1<pT<2 2<pT
Counts in cosine(theta*) bins • Evaluate the crossfeed in 2 parts of cosine(theta*) : • [-.6;.6] : used in production • [-1;-.6]U[.6;1] • no dependence of cross feed for central part of cosine(theta*) vs pT D0 crossfeed ~0.45 • Slight dependence (decrease) of cross feed for peripheral values of cosine(theta*) vs pT D0